<!DOCTYPE html>
<html lang="zh-CN">
  <head>
    <meta charset="UTF-8" />
    <meta name="viewport" content="width=device-width, initial-scale=1.0" />
    <title>Document</title>
    <style>
      .outer {
        width: 400px;
        height: 400px;
        padding: 50px;
        background-color: gray;
        /* border: 1px solid green; */
        margin: 0 auto;
      }
      .inner {
        width: 100px;
        height: 100px;
        background-color: yellow;
        margin: 10px;
        /* border: 1px solid red; */
      }
      span {
        background-color: red;
      }
      .pr {
        margin-left: 30px;
        margin-right: 30px;
        /* margin-top无效; */
        margin-top: 100px;

        /* margin-bottom无效; */
        margin-bottom: 100px;
      }
      .spanabc {
        width: 200px;
        background-color: red;
        margin: 0 auto;
        display: inline-block;
        padding: 10px;
      }
    </style>
  </head>
  <body>
    <!-- 子元素的margin是参考父元素的content计算的 -->
    <span class="spanabc">abc</span>
    <!-- <div class="outer">
      <div class="inner"></div>
    </div>
    <span>前端</span><span class="pr">产品经理</span><span>运维总监</span> -->
  </body>
</html>
